During 1995, we have continued studies dealing with the neuroanatomical organization of the primate limbic system. We have completed studies of the cholinergic innervation of the Macaca fascicularis hippocampal formation and also examined the effects of transecting the main subcortical projection system on the distribution of cholinergic markers. Additional studies have used immunohistochemical techniques and in situ hybridization to investigate the distribution of GABAergic systems in the hippocampal formation. Our studies on the monkey amygdaloid complex have included examining the intrinsic connections of the lateral nucleus, the interconnections of the amygdala with the perirhinal and parahippocampal cortices and the origin of cortical connections to the amygdala. The latter study employed complementary anterograde and retrograde neuroanatomical techniques. In a new technical development in the laboratory, we have employed combined retrograde tracing technology with in situ hybridization for the demonstration of putative GABAergic neurons. This has allowed us to determine that the subcortical projections of the central nucleus are at least partially GABAergic. This technique will now be used with more frequency to determine the chemoanatomy of defined amygdaloid and hippocampal connections.